Biofuels, such as ethanol, biodiesel, and the like, show promise as an abundant source of renewable energy, but only if they can be produced at competitive prices. Some conventional methods for the production of biofuels may use high sugar feedstocks, such as corn, sugar cane, and the like. Because these feedstocks are also consumed by humans and livestock, using such materials for the production of biofuels may result in a shortage of supply which can increases the cost of the biofuel.
In order to create a biofuel from feedstock, one key step in the process requires the breaking down, or lysis, of the cell walls of the feedstock to release the carbohydrates, oil, lipids, and other compounds stored therein which is then processed downstream by enzymatic treatment to create a biofuel. Conventional methods to perform cell lysis on feedstock often rely on acids and steam which are dangerous and expensive.
Another conventional method for the production of a commonly known biofuel, ethanol, typically uses feedstock, such as sugarcane, or starch from corn. Producing ethanol from sugar or starch is well known but requires feedstock as the raw materials. Ethanol may also be produced from non-feedstock materials, often referred to as cellulosic material, e.g., corn stover or switch grass. Producing ethanol from cellulosic materials typically relies on pre-treating the cellulosic material to remove the lignin sheath from the cells which makes the cellulose, or carbohydrate, therein assessable. The cellulose is then broken down into its component sugars through hydrolysis and the resulting sugars are fermented to make ethanol. Such a technique is expensive, and cumbersome.
Biofuels may also be produced from small aquatic plants, such as algae or phytoplankton. Small aquatic plants store oil and lipids inside that cells which can be used to produce biofuels. However, liberating the oil and lipids from small aquatic plants in a cost-effective, continuous, manner is quite difficult. One conventional process for the extraction of oil and lipids from algae relies on drying the algae and extracting the oil and lipids using hexane or supercritical fluid CO2. Such a technique is expensive, difficult to perform in a continuous flow process, and uses dangerous and toxic materials.
PEF treatment is a process which uses short, high voltage pulses of electricity and a specialized treatment chamber to disrupt cell membranes in a process called electroporation. See e.g., U.S. Pat. No. 5,690,978 entitled “High Voltage Pulsed Electric Field Treatment Chamber For The Preservation Of Liquid Food Products”, incorporated by reference herein. As disclosed therein, PEF is used to expand and rupture pores in the cell membrane of bacteria or microorganisms to kill them and preserve liquid food products.
However, to date, PEF has not been used for continuous enhanced extraction of oil and lipids, as well as other valuable compounds from small aquatic plants to produce a biofuel.